Quick-break heavy duty switch using blade type fuses



Oct. 27, 1959 R. s. RAGAN 2,910,563

QUICKBREAK HEAVY DUTY SWITCH USING BLADE TYPE FUSES Filed Nov. 15, 1957 5 Sheets-Sheet 1 0 Q Q 942 Q 0 INVENTOR.

Bail-7 466 J BY R. S. RAGAN Oct. 27, 1959 QUICK-BREAK HEAVY DUTY SWITCH USING BLADE TYPE FUSES Filed Nov. 15, 1957 5 Sheets-Sheet 2 Oct. 27, 1959 R. s. RAGAN 2,91

QUICK-BREAK HEAVY DUTY SWITCH USING BLADE TYPE FUSES Filed Nov. 15, 1957 3 Sheets-Sheet 3 INVENTOR. 45667" .5 464 QUICK-BREAK HEAVY DUTY SWITCH USING BLADE TYPE FUSES Robert S. Ragan, incinnati, Ohio Application November 15, 1957, Serial No. 696,690 7 5 Claims. (Cl. 200-133) This application is a continuation-in-part of my copending application Ser. No. 552,835, filed December 13,

United States Patent 1955, which is entitled Cam-Actuated, Quick Break 7 Electric Switch, which has resulted in Patent 2,842,640.

The present invention relates. to a quick-break heavy duty electric switch especially adapted to use blade-type cartridge fuses. The previous application, while not limited thereto, disclosed a form adapted to ferrule type cartridge fuses.

The form of switch herein disclosed incorporates several valuable features which contribute to a greater degree of safety and expeditious handling and manufacture than is possible with the previous form.

Briefly stated, my improved switch incorporates a block which carries a blade type of fuse for each conductor line to be bridged or interrupted, this block being capable of being pressed against spring pressure onto a corresponding number of terminal-carrying frames. A novel form of double cam creates this pressure on the block against the frames to close the circuits (which may be phases of the same circuit) simultaneously and to lock the block in closed position. When it is desired to open the circuits, the spring-pressure does so quickly in order to snuff incipient arcs, but governs the extent of release of the block so that the latter cannot be ejected so violently that it might strike the door of the switch box hard enough from the inside to open the door and so permit the block to be lost. "It is retained out of electrical contact but can be quickly restored thereto by partial rotation of the switch handle.

Another advantage is the provision of a large handgrip on the top surface of the block which renders handling of the block easier when it is necessary to change fuses. Thehandgrip also acts as a rigid spacer to hold the fuses rigidly in alignment.

Another advantage is the provision of balanced spring ing throughout the construction of the switch so that a minimum of manual effort is required to insert and disengage the fuse-carrying block, but that such disengaging action must be deliberate, not inadvertent.

Referring now to the accompanying drawings:

Fig. l is a plan view of the switch with the block locked into electrical contact.

Fig. 2 is a corresponding but fragmentary view with the contact block removed.

Fig. 3 is a vertical cross section of the switch taken on line ..3 of Fig. 2, the lever and lever spring assembly being added. The switch shown in contact or locked position.

Fig. 4 is a vertical cross section corresponding to Fig. 3 but with the switch in the open position, the block being not yet completely separated from the frames.

Fig. 5 corresponds to Figs. 3 and 4 except that the operating lever is fully retracted so that the cams release the 2,910,563 Patented Oct. 27, 1959 Fig. 7 is a detail of the left hand side of Fig. 6 showing the locked or contact making position of the switch as in Fig. 3.

Fig. 8 is a detail in plan and is an unobstructed view of the end of a blade type cartridge fuse held in the removable block by a pivoted conductive latch.

In Fig. 1, 10 is a steel box having a side-hinged lid 11 (shown as a fragment). To the bottom of box 10 there are afiixed by rivets 12 or other means, a plurality of steel springs 13 which are elevated from the box surface at 14 (elevation indicated by shading). This construction can be more clearly seen in Figs. 3 to 6, inclusive. Upon each spring there is mounted a frame 15 (see Figs. 3 to 6) of dielectric material which has the shape of a sharp angled U. The purpose of each spring and frame is to provide a support for a fuse-carrying block 16, also of dielectric material, and to provide two electric terminals 17 and 18 for contact with each fuse 19 through which is to flow the electric current which represents one phase of a multi-phase circuit. In this case, a switch for three phase current is shown. The fuses 19 are of the cartridge type provided with blade terminals 20 (see Figs. 3 to 6) and are carried in the block 16 which is intended to make contact with terminals 17 and 18 by being pressed vertically thereto. Contact of the fuse blades 20 with the terminals17 and 18 is indirect through a conductive fuse retainer 21 which is pivoted at one of its corners 22 to the lower surface of the block 16 (see Figs. 6, 7 and block, which is in process of being lifted out manually.

8). This surface is provided with a fiat bottomed depression for the reception of the fuse blade 20 so that the retainer 21 may slide over the blade smoothly and tightly. A drilled hole 23 (Fig. 8) for'a screw driver or other tool rs provided to disengage the retainer 21 for fuse removal and to lock the retainer. Thus provision is made for the secure retention of fuses in the block 16 coupled with ease of replacement and adequate electrical contact. An arched handle 24 of dielectric material is provided across the top of the block 16 with sufiicient clearance so that the block may be lifted without touching the fuses or other live conductors. The block 16 may then touch the inside of the lid 11 without imparting a charge thereto, since only the handle will make contact therewith.

As will be seen in Figs. 2 to 6 inclusive, the box 10 is traversed at its mid-section by a shaft 25 upon which are rigidly mounted symmetrical cams 26, the inner rims of which serve as contacting surface for rollers 27 which are attached to the lower and outer edges of the block 16. The camming action created by rotation of the shaft 25 upon manual actuation of a handle 28 to which it is rigidly attached, forces the block 16 downward by pushing on the rollers 27,thus forcing the contacts 21 and 1718 together with a considerable degree of pressure.

From Fig. 3 which shows the switch in section in the locked or conducting position just described, it will be seen how the peculiar shape of the cam 26 contributes to exceptionally stable and vibration-proof conductivity. The inner surface of cam 26 contacts roller 27 on the fuse-carrying block 16 at that portion of the cam in which the radius is shorter than at the opposite end of the cam surface. In locked position the cam surface extends over the roller 27 well beyond the vertical line joining the centers of rod 25 and of a short stud 29 upon which the roller 27 is mounted on the block 16. The block is therefore held down by the roller and its stud beyond any possibility of springing upward even though the fiat springs 13 upon which the frame 15 are pressing upward with considerable force, thus insuring excellent electrical contact between the fuse blades '20 and the terminals 17 and 18. in this state of affairs, it is to be observed that the handle 28 lies low. There is no. spring pressure tending to lift the handle out of this position from a pair of rods 30, one of which is attached to each cam 26 near the end of larger radius as shown in Figs. 1, 2 and 3. The rods 30 each pass through tabs 31, one of each of which is pivotably mounted on the inner surface of the box 10. Each rod 30 is provided with an outer stop disc 32 and an inner stop disc 33. The discs 32 and 33 are immobile to act as limits for two coil springs 34 and 35, outer and inner, respectively, which encircle the rod 30, one on each side of the tab 31. With such arrangement, it is possible to provide spring assistance to handle movement for every position of the handle 28 except when it is in locking position as shown in Figs. 1 and 3 and discussed above.

In order to interrupt electrical contact'between the fuses 19 and the terminals 17 and 18, the handle 28 is swung 180 from the position shown in Figs. 1 and 3 to the position shown in Figs. 2 and 4. This motion necessitates compression of the spring 34 and the pivoting of the tab 31 (see Fig. 4). The handle 28, once it arrives 180 from whence it started, is held there by spring pressure. The block 16 rises under pressure of a pair of comparatively weak coil springs 36 (see Figs. 6 and 7) which are mounted vertically on spindles 37 which are upset to a mushroom shape on both ends and are slidable through their mounts 38 on the outer sides of the outer frames 15. Fig. 7 shows the position of this assembly when the switch is locked into conductivity. Fig. 6 shows the assembly open, the block being lifted up out of conducting position, and ejected. As previously mentioned, it is undesirable to eject the block forcibly enough to knock the door of the switch box open because to do so might create a hazardous exposure of live terminals and might also lead to loss of the block. So the ejection is arranged to occur in stages as will appear from the following.

In order to change fuses it is definitely necessary to take the block 16 out of the frame 15 and box 10 so that it may be turned upside down for convenience. To release the block, the handle 28 is turned counterclockwise in reference to Figs. 4 and to a position more than 180 away from that shown in Fig. 3. Spring 34 is then compressed to the limit and cam 26 is tilted far enough to let the roller 27 escape from theinner cam surface of longer radius. The spindles 37 under the urge of springs 36 now extend themselves fully in place of the partial extension that occurs when the block is in the position shown in Figs. 4 and 6. In this position, the handle touches or nearly touches the inner surface of lid 11, but does not strike or push it hard enough to open the box while still achieving a quick break. A vertical rise of the block 16 with reference to the general assembly of the switch is assured by vertical slots 39 in guides 40, one thereof being located on the block edges so as to straddle the rod 25 between the frames and earns 26.

Counterbalancing of forces is achieved by making the springs 34 when fully compressed approximately but not quite equal in push to the upward force of the three springs 13 when they are in the intermediate position shown in Fig. 4. '-It then takes a minimum of effort to move the handle 28 to achieve either position of Fig. 3 or Fig. 5. I

Leads L to the switch have been shown in Fig. 1 and their location may be varied to pierce any side 'of the box 10. The leads may, however, make contact with the terminals 17 and 18 in any appropriate manner, which is the reason that these pieces have been shown extended to provide latitude.

I claim as my invention:

1. :In an electric switch, a plurality of frames, an electrical contact on each end of said frames, a block adapted to fit into said frames, a plurality of fuses carried within said block for bridging the contacts on said frames, internally engaged cam means for bringing said block into close electrical contact with said fuses to bridge said contacts and ejection means for said block capable of merely separating said block from said contacts or of gently ejecting said block from said frame, the degree of removal of said block being governed by the selected position of said cam means.

2. In an electric switch, a box, a plurality of insulating frames mounted within said box, electrical terminals carried by each frame at opposite ends thereof, an insulating block adapted to fit upon said frames, electric fuses carried by said block and arranged thereon to bridge the contacts on said frames, a double internally engaged cam mounted within said box for engaging and forcing said block and fuses into pressure engagement with the terminals on said frames, means on said block for providing engagement for said cam, a handle and shaft therefor extending outside said box for rotating said cam, the cam being shaped to provide selectively, pressure on said block, limited upward release of said block or optional manual total removal of said block from said frames and box.

3. In an electric switch, a box, a plurality of insulating frames mounted within said box, electrical supply terminals carried by each frame at opposite ends thereof, an insulating block adapted to fit upon said frames, electric fuses carried by said block and arranged thereon to bridge the contacts on said frames, a pair of internally engaged, substantially semicircular cams mounted within said box, one cam on each side thereof for engaging and forcing said block and its associated fuses into electrical engagement with said terminals on said frames, means on said block for providing internal engagement for said cams, a shaft for supporting and rotating said cams, a handle on said shaft outside the box for actuating said earns, a pair of rods one attached to each cam, pivoted tabs attached to the inner side of said box for guiding the outer end of said rods, a pair of coil springs encircling said rods within stop limits, one spring being disposed on each side of said tab, whereby to provide an assisting and cushioning force when said handle is used to operate the cams.

4. In an electric switch, a box, a plurality of insulating frames mounted within said box, electrical terminals carried by each frame at opposite ends thereof, an insulating block adapted to fit upon said frames, means for retaining electric fuses on the lower surface of said block whereby said fuses may electrically bridge the contacts on said frames when said block is fitted to said frames, roller means on the sides of said block, a pair of internal-surface-type cams mounted in said box, one cam on each side of the frame assembly, said cams being adapted to engage said block by said roller means, a shaft extending outside said box upon which said cams are mounted for pulling said block into electrical engagement with said frame terminals, a handle mounted on said shaft on the outside of said box for rotating said shaft and cams, guide means on said block arranged to straddle said shaft and to constrain said block to take a vertical path during engagement with said frame terminals and spring means connecting at least one cam and the box for giving the block a quick but limited upward push to break electrical contact upon actuation of said handle from fully closed position and to release said block from said frame entirely upon further actuation of the handle past the 180 point.

5. In an electrical switch of the type in which a plurality of frames bearing electrical terminals at opposite ends thereof is provided with a vertically movable insulating block which bears fuses, the improvements upon said block which comprise electrical terminals adapted to make contact with the blades of said fuses and to hold said fuse blades into recesses in the insulating material of said block, said terminals being made of flat conducting metal, a'pivot for swinging said terminal over the recess in the block which contains the fuse blade and means for fastening the swinging terminal in close contact with the fuse 6 blade onto the fuse block at the non-pivoted side of the 2,289,358 Hanny July 14, 1942 terminal. 2,475,341 Steinmayer July 5, 1949 2,635,151 Sharp Apr. 14, 1953 References Cited in the file of this patent 2,331,033 K b A 15, 1958 UNITED STATES PATENTS 5 FOREIGN A S 461,761 Lean Oct. 20, 1891 207,956 Great Britain Dec. 13, 1923 1,733,126 Johansson Oct. 29, 1929 348,829 Great Britain May 21, 1931 1,835,983 Hammerly Dec. 8, 1931 807,708 France Oct. 19, 1936 

